1. Field of the Invention
The present invention relates to an elastic composite material and a mold product using the same, more particularly, to an elastic composite material having both the coefficient of friction equivalent to that of fluorine resin and the specific wear rate equivalent to that of ultra-high molecular weight polyethylene while having rubber elasticity.
2. Description of the Related Art
Conventionally in the field of industrial sheets, especially for applications requiring a lower coefficient of friction as compared with rubber monolayer sheets, the composite sheets comprising a rubber layer and a layer of fluorine resin such as PTFE (polytetrafluoroethylene) or a layer of ultra-high molecular weight polyethylene with the molecular weight of 1,000,000 or more which is laminated on the rubber layer have been widely used. These composite sheets are excellent in elasticity and flexibility compared with monolayer sheets including fluorine resin or ultra-high molecular weight polyethylene. Therefore, the workability in e.g. bonding with other members is particularly improved because of the presence of the rubber layer.
However, in such industrial composite sheets, on one hand, the composite sheet comprising a fluorine resin layer has drawbacks in that the specific wear rate of the composite sheet comprising the fluorine resin layer is greater than the specific wear rate of the composite sheet comprising the ultra-high molecular weight polyethylene layer. On the other hand, the composite sheet comprising an ultra-high molecular weight polyethylene layer has drawbacks in that the coefficient of friction of the composite sheet comprising the ultra-high molecular weight polyethylene layer is greater than the coefficient of friction of the composite sheet comprising the fluorine resin layer. In addition, there is also a disadvantage in that powder material or the like which is easily charged with electricity may be adsorbed on the composite sheet by static, since the volume resistivity values of the fluorine resin and ultra-high molecular weight polyethylene are large.
In recent years, although the composite industrial sheets having all the characteristics of low friction, wear resistance, electrical conductivity and softness (flexibility) have been demanded in order to apply such composite sheets for the use such as sticking resistance (for nonstick material), the industrial sheets satisfying all the above characteristics have not been achieved yet.
On the other hand, as a material with low coefficient of friction and excellent abrasion resistance, defatted bran ceramics (e.g. trade name “RB ceramics” of Sanwa Yushi Kabushiki Kaisha) which is a porous carbon material produced by kneading defatted bran such as defatted rice bran or defatted wheat bran with thermosetting resin, and the kneaded mixture has been remarked. For example, JP-A2003-253132 and JP-A 2004-108499 disclose the low friction synthetic resin composite material comprising fine particles of “RB ceramics” dispersed in synthetic resin, respectively.